The captured touch screen data could be used to reconstruct what users typed

Security researchers identified a vulnerability in iOS that allows apps to record all touch screen and button presses while running in the background on non-jailbroken devices.

Since the touch screen is the primary input interface on an iOS device, this attack is the equivalent of keylogging. An attacker could use the captured touch data -- X and Y axes coordinates -- to determine what characters victims inputted using the on-screen keyboard.

The vulnerability has been confirmed in iOS versions 7.0.6, 7.0.5, 7.0.4 and 6.1.x by researchers from security firm FireEye who identified the issue and reported it to Apple. The researchers also claim they found ways to bypass Apple's app review process which could allow uploading an app with such touch screen monitoring capabilities in the App Store.

"We have created a proof-of-concept 'monitoring' app on non-jailbroken iOS 7.0.x devices," the FireEye researchers said Monday in a blog post. "This 'monitoring' app can record all the user touch/press events in the background, including, touches on the screen, home button press, volume button press and TouchID press, and then this app can send all user events to any remote server."

Attackers could use social engineering techniques to trick victims into installing a malicious app or they could exploit some vulnerability in an existing app to use it for this type of background monitoring, the researchers said.

IOS 7 allows users to control which apps are allowed to refresh their content while running in the background, but there are ways to bypass that restriction, according to the FireEye researchers.

"For example, an app can play music in the background without turning on its 'background app refresh' switch," the researchers said. "Thus a malicious app can disguise itself as a music app to conduct background monitoring."

The best way to avoid this security issue in the absence of a patch from Apple is to use the iOS task manager to close apps operating in the background, the researchers said.

This is not the first research about recording touch screen events. Neal Hindocha, a senior security consultant at Trustwave, plans to demo "touchlogging" apps for Android and iOS at the RSA security conference Wednesday. However, his iOS proof-of-concept app requires the targeted device to be jailbroken, unlike FireEye's attack.

The FireEye researchers said they've conducted their research independently of Hindocha's and without being aware of his plans.